A. Morral et al.
10.00
9.00
8.00
206
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Basal
1 month
Group I- Standard device
2 months
4 months
Group II- Sophisticated Device
14 months
Group III- Austere device
Fig. 6. Visual analogue scale (VAS) assessment of pain during the day,
over time and by device group. Time factor p < 0.001; device factor
p = 0.853; device–time interaction factor p = 0.599.
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Basal
Group I- Standard device
4 months
Time
Group II- Sophisticated Device
14 months
Group III- Austere device
Fig. 7. Fascia thickness over time and by device group. Time factor
p < 0.001; device factor p = 0.402; device–time interaction factor
p = 0.800.
Therapeutic context includes a multitude of signals
inherent to any intervention, which are perceived and
interpreted by patients and generate positive or nega-
tive expectations (12). Placebo and nocebo effects can
be generated from expectations (27–29); therefore it is
important to assess contextual factors that can generate
expectations and their impact on clinical outcomes.
This RCT was designed to evaluate the influence of
the appearance of a physical agent; in this case a rESW
device, on clinical outcomes in plantar fasciitis.
It was found that, in the treatment of chronic plantar
fasciitis with rESW, the appearance of the device did
not significantly affect the clinical results. None of
the 5 clinical variables analysed (foot function, pain
with the first weight-bearing step in the morning, pain
during the day, plantar fascia thickness, and adverse
effects) showed statistically significant differences bet-
ween the 3 groups: patients had similar results regard-
less of the treatment device (standard, sophisticated,
www.medicaljournals.se/jrm
or austere device). Furthermore, all patients improved
significantly over time in relation to the baseline assess-
ment. The improvement was observed equally in all 3
groups and at all assessment time-points: 1, 2, 4 and 14
months after the last rESWT session, with no statisti-
cally significant differences among groups over time.
That is, the clinical outcomes were independent of the
device used. Although the appearance of the device
neither improved nor worsened treatment outcomes, as
shown in this study, small differences were observed
between the austere group and the other groups. The
austere group obtained, in most evaluations, the worst
clinical outcomes.
Despite an extensive neuroscience base that supports
the placebo effect, there is a lack of clinical research
that explores, in a healthcare setting, the context and
placebo responses that accompany the overall thera-
peutic intervention. Most existing knowledge about the
placebo effect has come from studies in basic science
and clinical trials that are far removed from usual clini-
cal practice. However, it has been found that placebo
responses are greater under these conditions than in
clinical trials conducted in real healthcare settings (21).
Few clinical trials have analysed treatment context
factors, such as the appearance of a physical agent
and its possible influence on patient recovery, making
it difficult to compare the results of the current study
with those obtained in similar studies. In a study con-
ducted by Dawes et al. (30), 2 identical hearing aids
were compared: 1 described as “new” and the other as
“conventional”. Approximately 75% of the participants
preferred the new device and reported that the hearing
quality it provided was superior to the conventional
one (30). Another clinical trial, with real patients,
investigated the influence of different verbal infor-
mation combined with a real analgesic drug (31) and
reported similar results to the present study, showing no
differences in pain reduction. Furthermore, in a cros-
sover clinical trial, it was shown that the same person
may respond differently to different types of placebo
(placebo tablet or sham acupuncture). The response
to placebo is a complex phenomenon that has many
variables and goes beyond patient characteristics. This
could explain the difficulty of detecting a pattern for
people “responding to placebo” (32, 33).
The magnitude of the placebo effect depends on
numerous design factors. A 2015 meta-analysis found
that the type of active drug (opioid or non-steroidal
anti-inflammatory drug (NSAID)), the scheduled
follow-up visits (number of planned face-to-face vi-
sits), and randomization ratio (probability of receiving
a placebo treatment, 1:4 or 1:1) were predictive of the
magnitude of the placebo response, thereby supporting
the expectancy hypothesis. Exploratory models sho-